Re: [Simpledb-general] StringColumn Length Question (SDB ver 1.13)

[Russell K. <ru...@kl...>]

I had a look into the crash issue, and it was a buffer overflow with the
buffer size being setup incorrectly. It's a bit scary that this wasn't
discovered earlier. It showed up using valgrind. You can see the simple
fix made by following the link below:

http://simpledb.svn.sourceforge.net/viewvc/simpledb/trunk/SimpleDB/StringColumn.cpp?r1=10&r2=18

A new release with this fix has now been made available on sourceforge:

https://sourceforge.net/projects/simpledb/

I look forward to your DynamicStringColumn :)

Cheers,

Russell

On Thu, 2010-06-24 at 09:48 -0700, Bruce Bailey wrote:
> Russell
> 
> Thanks very much for the reply.  Writing a 'DynamicStringColumn' class
> is intriguing and I may take that on.
> 
> I'll take your advice and simply set a bigger column size and hope for
> the best.  Extracting a row of data and putting it in another,
> dynamically sized structure isn't too hard and that way I get the best
> of both worlds -- efficient space utilization and use of SimbleDB.
> 
> In case it helps, I am including a simple duplication example
> (base64/bzip2).
> 
> On windows, using VS2008, it simply crashes on exit.
> On RH Linux (somewhat older) it returns 6 characters (1 greater than
> the buffer size), no errors or exceptions.
> 
> 
> _=_ 
> _=_ Part 001 of 001 of file sdb.cpp.bz2
> _=_ 
> 
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> +wGOa1Gh3ZM9
> //F3JFOFCQlh2Ffw
> 
> 
> 
> Bruce
> 
> > Subject: Re: [Simpledb-general] StringColumn Length Question (SDB
> ver 1.13)
> > From: ru...@kl...
> > To: bru...@ho...
> > CC: sim...@li...
> > Date: Thu, 24 Jun 2010 10:37:57 +1000
> > 
> > > It appears that if you set the size of the buffer too small for a
> > > given field (i.e. data type of 'text'), that the program will
> crash --
> > > presumably due to buffer overrun.
> > 
> > Setting a buffer too small shouldn't cause a buffer overrun. If it
> does,
> > then it is a bug that needs to be fixed. Are you sure it isn't
> throwing
> > an exception?
> > 
> > > What is the conventional wisdom for using StringColumn where the
> > > length isn't known?
> > > 
> > > Should I just allocate a very large buffer and hope for the best?
> > > Are there plans for a DynamicStringColumn class?
> > 
> > Until now, I have been just setting a reasonable sized buffer. A
> > DynamicStringColumn class would be great! Feel free to send a patch.
> > 
> > Cheers,
> > 
> > Russell
> > 
> 
> 
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